ptg10805159622 Network IPC: Sockets Chapter 16
Example — Connectionless Ser ver
The program in Figure16.20 is the datagram version of theuptimeserver.
#include "apue.h"
#include <netdb.h>
#include <errno.h>
#include <syslog.h>
#include <sys/socket.h>
#define BUFLEN 128
#define MAXADDRLEN 256
#ifndef HOST_NAME_MAX
#define HOST_NAME_MAX 256
#endif
extern int initserver(int, const struct sockaddr *, socklen_t, int);
void
serve(int sockfd)
{
int n;
socklen_t alen;
FILE *fp;
char buf[BUFLEN];
char abuf[MAXADDRLEN];
struct sockaddr *addr = (struct sockaddr *)abuf;
set_cloexec(sockfd);
for (;;) {
alen = MAXADDRLEN;
if ((n = recvfrom(sockfd, buf, BUFLEN, 0, addr, &alen)) < 0) {
syslog(LOG_ERR, "ruptimed: recvfrom error: %s",
strerror(errno));
exit(1);
}
if ((fp = popen("/usr/bin/uptime", "r")) == NULL) {
sprintf(buf, "error: %s\n", strerror(errno));
sendto(sockfd, buf, strlen(buf), 0, addr, alen);
}else {
if (fgets(buf, BUFLEN, fp) != NULL)
sendto(sockfd, buf, strlen(buf), 0, addr, alen);
pclose(fp);
}
}
}
int
main(int argc, char *argv[])
{
struct addrinfo *ailist, *aip;
struct addrinfo hint;
int sockfd, err, n;
char *host;